Terminal gate and ramp areas in today's airports can be very congested places, with simultaneously arriving and departing aircraft and ground service vehicles and ground personnel servicing and directing aircraft into and out of gates. The avoidance of collision incidents in this area requires careful monitoring and control of the locations and movement of aircraft and other vehicles as they maneuver within these areas. The pushback of departing aircraft must be guided with even more care because the aircraft is moving in reverse, and the pilot and flight crew are not able to see the entire environment surrounding the aircraft. The sides and rear of the aircraft, in particular, cannot be seen by the pilot and crew from the cockpit. Currently, aircraft are pushed back with tow vehicles or tugs, and the tug driver is assisted by a number of ground personnel to guide and move the aircraft in reverse as it is simultaneously being turned to a location where the aircraft can start its engines and move forward to a taxiway. At many, if not most, airports, the environment surrounding the aircraft is monitored by these ground personnel and the tug driver, who communicate its status to the pilot through universal visual signals and, at some airports, through additional voice communications. Aircraft pushback, as it presently conducted, is a time and labor-intensive process that all too frequently produces delays in an airline's flight schedule.
Airport ground personnel are typically assigned to attach and detach tow vehicles and to monitor and direct reversing aircraft to ensure that no part of an aircraft structure will impact any fixed object or other aircraft or vehicle. These or other ground personnel may, in addition, communicate directly with the pilot or another aircraft cockpit crew member during the pushback process. The efficiency and speed with which pushback can be conducted depends on the availability of ground personnel as well as the availability of tow vehicles.
The efficiency and speed of aircraft pushback operations tends to be adversely affected by the ground congestion found in most large airports. Multiple airlines concurrently conduct both pushback and arrival operations for multiple aircraft. This strains not only the available towing equipment, but also the available ground personnel. Aircraft turnaround times may be increased significantly when tow bars, adapters, tugs, or ground crew personnel are not available for pushback when needed.
Driving an aircraft on the ground during taxi without reliance on operation of the aircraft's main engines or the use of tow vehicles has been proposed. For example, in commonly owned U.S. Pat. No. 7,469,858 to Edelson; U.S. Pat. No. 7,891,609 to Cox; U.S. Pat. No. 7,975,960 to Cox; U.S. Pat. No. 8,109,463 to Cox et al; and British Patent No. 2457144, aircraft drive systems that use electric drive motors to power aircraft wheels and move an aircraft on the ground without reliance on aircraft main engines or tow vehicles are described. A powered self pushback method and system in which aircraft are equipped with such drive systems is described in commonly owned International Patent Application Publication No. WO2012109380 A2. This powered self pushback method is designed for moving an aircraft parked in a nose-in orientation along a reverse path while simultaneously turning the aircraft in the same direction and along the same path as the aircraft would be pushed back with a tug. It is not suggested that an aircraft could travel in reverse along a path essentially perpendicular to a terminal or away from a gate without simultaneously turning, or that an aircraft could turn in a different direction so that the aircraft may taxi forward to a takeoff runway upon turning.
Sensors, including cameras and the like, have long been mounted on exterior locations on aircraft to monitor various aspects of an aircraft's exterior environment or an aircraft's ground maneuvers. In U.S. Pat. No. 6,405,975, for example, Sankrithi et al describe a camera system mounted to provide real time video images of the ground surrounding an aircraft nose or main landing gear to assist the aircraft pilot in maneuvering an aircraft with a wide wheel track, a long wheel base, or both during turns and gate entry. U.S. Pat. No. 7,049,953 to Monroe describes a plurality of strategically placed sensors, including video imaging generators, audio sensors, motion detectors, and smoke and fire detectors, primarily for remotely monitoring aircraft security, but also to monitor aircraft ground movement to avoid collisions when ground vehicles are outfitted with GPS receivers. Aircraft ground collision avoidance systems have also been described in the art. The WingWatch system, described at www.wingwatch.com, employs a system of cameras mounted on an aircraft that use computer vision techniques to provide a live, dynamic map of an aircraft's surroundings to detect obstacles that might pose a collision threat to an aircraft moving on the ground. A caution or warning indication in the form of acoustic cues and visual information is provided to the aircraft's pilot when an obstacle is detected. None of the foregoing art, however, suggests a method for monitoring a streamlined, accelerated pushback process or autonomous reverse ground travel in an aircraft equipped with an engines-off taxi system, wherein the aircraft is driven safely in reverse along an optimum path and turned at an angle that expedites pushback, so that it may then be driven forward for takeoff. A need exists for such a method.